Color image recording and reproducing system

ABSTRACT

A spectral image photographing section photographs the image of an object to be photographed as spectrum information in units of pixels so as to mutually record and reproduce a faithful image between two points. A photographing light spectrum detecting section detects the spectrum distribution of illumination light at a photographing point. A reproduction environment light spectrum detecting section detects the spectrum distribution of illumination light at a reproduction point. A spectral reflectance distribution calculating section eliminates the influence of the spectrum distribution of illumination light from the spectrum information photographed by the spectral image photographing section, and calculates the spectral reflectance distribution of the object. A spectrum converting section calculates, on the basis of the reproduction environment light spectrum detected by the reproduction environment light spectrum detecting section and the spectral reflection distribution calculated by the spectral reflectance distribution calculating section, a spectrum distribution obtained when the image of the object is photographed under illumination light substantially identical to that at the reproduction point. A vector imaging section converts the spectrum distribution of each pixel converted by the spectrum converting section into three-dimensional color.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a color image recording and reproducingsystem and, more particularly, to a color image recording andreproducing system using a color matching technique for matching displaycolors displayed under different ambient illumination conditions in acolor matching technique of matching the color of a target object andits display color.

2. Description of the Related Art

Conventionally, accurate color reproduction is not taken intoconsideration in a television (TV) system for transmitting andreproducing a photographed color image. Only a visual image quality inreproduction is considered.

To reproduce an image photographed at a remote place with accuratecolors, it is not sufficient to process the image by the camera to thedisplay system without any distortion and error. The image must bereproduced in the environment wherein the image is illuminated by alight source having the same spectrum as that on the photographing side.

However, it is actually very difficult to prepare an illumination havingthe same spectrum on the photographing and reproduction sides.

In a technique of matching "three-dimensional" colors under almost thesame conditions as those of three stimulus values represented by R, G,and B in order to perform color matching, which is known as a prior art,it is difficult that the color matching results accurately coincide witheach other.

The reason is that there are color matching conditions.

More specifically, even if the spectrum is the same, a so-called XYZcolorimetric system, i.e., three color matching functions (colormatching functions of an XYZ colorimetric system), like the ones shownin FIG. 8, are actually present as a human visual function. Actually,the spectrum is multiplied by this function to calculate an integratedvalue.

For this reason, even when a color is visually observed as a given colorunder a certain illumination, if the spectrum distribution changes, thiscolor is observed as another color under another illumination.

Various attempts have been made to obtain the colors of printed matteror colors displayed on a TV monitor to be closer to colors visuallyrecognized by man.

On the other hand, as the DTP system (Desk-ToP publishing; electronicpublishing) has been spread with recent higher-performance andsmaller-size computers, color matching techniques (e.g., Jpn. Pat.Appln. KOKAI Publication Nos. 5-216452 and 6-51732) of matching thecolors of printed matter as an input/output target with display colorsdisplayed on a TV monitor have been proposed.

These prior arts disclose a color matching technique of matching thecolors of printed matter as an input/output target with display colorsdisplayed on a TV monitor under various different ambient illuminationconditions.

In either prior art, the display and printing places are assumed to beat the same point, i.e., under the same illumination conditions. Theseprior arts do not particularly disclose or indicate a technique of,e.g., reproducing by display or printing an image photographed at, e.g.,a different remote place apart from a reproduction place with accuratecolor reproduction, i.e., matching the color of a reproduced object,i.e., the color of a display screen or printed matter with the color ofthe photographed object under different illumination conditions.

Originally, if a color image recording and reproducing system having thesame transmission characteristics as the above-described three humanvisual properties is constructed, the color of a reproduced image isseen to be the same as the color of an object. However, since the visualproperties vary due to individual differences, the color of thereproduced image and the color of the object are not always matched witheach other for all people.

To completely match the color of the reproduced image with the color ofthe object in consideration of these situations (so as to allow anobserver to perceive these colors as the same color), necessity formatching the spectra is required.

SUMMARY OF THE INVENTION

Taking this necessity into consideration, the first object of thepresent invention is to provide a color image recording and reproducingsystem which reproduces (displays or prints) an image photographed at,e.g., a remote place different from a reproduction place with accuratecolor reproduction by using a color reproducing technique of alsomatching the spectra.

In addition to the first object, the second object of the presentinvention is to provide a color image recording and reproducing systemcapable of accurately reproducing a color without increasing theinformation amount transmitted between the photographing andreproduction places.

According to the present invention, there is provided a color imagerecording and reproducing system for reproducing, at a different remoteplace, an image recorded at an arbitrary place, characterized bycomprising spectral image photographing means for photographing anobject to be photographed as spectrum data in units of pixels,photographing light spectrum detecting means for detecting a spectrumdistribution (to be referred to as photographing light spectrum datahereinafter) of illumination light at a point where the object isphotographed by the spectral image photographing means, reproductionenvironment light spectrum detecting means for detecting a spectrumdistribution (to be referred to as reproduction environment lightspectrum data hereinafter) of illumination light of a point (to bereferred to as a reproduction point side hereinafter) where an image ofthe object photographed by the spectral image photographing means isreproduced, image converting means for converting, on the basis of thephotographing light spectrum data detected by the photographing lightspectrum detecting means and the reproduction environment light spectrumdata detected by the reproduction environment light spectrum detectingmeans, the spectrum data photographed by the spectral imagephotographing means into color image data equivalent to color image dataobtained when the object is photographed under illumination lightsubstantially identical to that on the reproduction point side, andcolor image reproducing means for reproducing the color image dataconverted by the image converting means.

According to the present invention, there is provided a color imagerecording and reproducing system for reproducing, at a different remoteplace, an image recorded at an arbitrary place, characterized bycomprising spectral image photographing means for photographing anobject to be photographed as spectrum data in units of pixels,photographing light spectrum detecting means for detecting a spectrumdistribution (to be referred to as photographing light spectrum datahereinafter) of illumination light at a point where the object isphotographed by the spectral image photographing means, spectralreflectance distribution calculating means for eliminating an influenceof the photographing light spectrum data detected by the photographinglight spectrum detecting means from the spectrum data photographed bythe spectral image photographing means, and calculating a spectralreflectance distribution of the object, reproduction environment lightspectrum detecting means for detecting a spectrum distribution (to bereferred to as reproduction environment light spectrum data hereinafter)of illumination light of a point (to be referred to as a reproductionpoint side hereinafter) where an image of the object photographed by thespectral image photographing means is reproduced, spectrum convertingmeans for calculating, on the basis of the spectral reflectancedistribution calculated by the spectral reflectance distributioncalculating means and the reproduction environment light spectrum datadetected by the reproduction environment light spectrum detecting means,a spectrum distribution obtained when the object is photographed underillumination light substantially identical to that on the reproductionpoint side, vector imaging means for converting a spectrum distributioncorresponding to each of the pixels calculated by the spectrumconverting means into three-dimensional color specification vector data,and color image reproducing means for reproducing a color image of theobject on the basis of the color specification vector data converted bythe vector imaging means.

According to the present invention, there is provided a color imagerecording and reproducing system characterized by further comprisingtransmitting means for mutually transmitting data on a point side wherethe image of the object is photographed, and data on a point side wherethe image of the object is reproduced.

According to the present invention, there are provided color imagerecording and reproducing systems for mutually recording and reproducingimages between first and second different points, characterized in thateach color image recording and reproducing system is constituted byspectral image photographing means for photographing an object to bephotographed as spectrum data in units of pixels, photographing lightspectrum detecting means for detecting a spectrum distribution (to bereferred to as photographing light spectrum data hereinafter) ofillumination light at a point where the object is photographed by thespectral image photographing means, spectral reflectance distributioncalculating means for eliminating influence of the photographing lightspectrum data detected by the photographing light spectrum detectingmeans from the spectrum data photographed by the spectral imagephotographing means, and calculating a spectral reflectance distributionof the object, reproduction environment light spectrum detecting meansfor detecting a spectrum distribution (to be referred to as reproductionenvironment light spectrum data hereinafter) of illumination light of apoint (to be referred to as a reproduction point side hereinafter) wherean image of the object photographed by the spectral image photographingmeans is reproduced, spectrum converting means for calculating, on thebasis of the spectral reflectance distribution calculated by thespectral reflectance distribution calculating means and the reproductionenvironment light spectrum data detected by the reproduction environmentlight spectrum detecting means, a spectrum distribution obtained whenthe object is photographed under illumination light substantiallyidentical to that on the reproduction point side, vector imaging meansfor converting a spectrum distribution corresponding to each of thepixels calculated by the spectrum converting means intothree-dimensional color specification vector data, and color imagereproducing means for reproducing a color image of the object on thebasis of the color specification vector data converted by the vectorimaging means, wherein the color image recording and reproducing systemsare respectively arranged at the first and second points, and the colorimage recording and reproducing systems further comprise transmittingmeans for mutually transmitting the reproduction environment lightspectrum data and the color specification vector data between the firstpoint and the second point.

According to the present invention, there is provided a color imagerecording and reproducing method of mutually recording and reproducingimages between first and second two different points, characterized bycomprising the spectral image photographing step of photographing anobject to be photographed as spectrum data at the first point in unitsof pixels, the photographing light spectrum detecting step of detectinga spectrum distribution (to be referred to as photographing lightspectrum data hereinafter) of illumination light at a point where theobject is photographed, the spectral reflectance distributioncalculating step of eliminating an influence of the photographing lightspectrum data from the spectrum data photographed in the spectral imagephotographing step, and calculating a spectral reflectance distributionof the object, the reproduction environment light spectrum detectingstep of detecting a spectrum distribution (to be referred to asreproduction environment light spectrum data herein-after) ofillumination light at the second point where an image of the object isreproduced, the reproduction environment light spectrum datatransmitting step of transmitting the reproduction environment lightspectrum data at the second point detected in the reproductionenvironment light spectrum detecting step to the first point, thespectrum data converting step of calculating, on the basis of thereproduction environment light spectrum data transmitted in thereproduction environment light spectrum data transmitting step, and dataof the spectral reflectance distribution calculated in the spectralreflectance distribution calculating step, a spectrum distributionobtained when the object is photographed under illumination lightsubstantially identical to that on the second point side, the vectorimaging step of converting a spectrum distribution of each of the pixelscalculated in the spectrum converting step into three-dimensional colorspecification vector data, and the color image reproducing step ofreproducing a color image of the object on the basis of the colorspecification vector data converted in the vector imaging step.

According to the above-described color image recording and reproducingsystem, a photographed image is reproduced upon converting the spectrumdata of the photographed image on the basis of the spectrum distribution(reproduction environment light spectrum data) of illumination light atthe reproduction point. For this reason, even if the object image isphotographed at, e.g., a remote place different from the reproductionplace, the object image can be reproduced by display or printing underaccurate color reproduction.

According to the above-described color image recording and reproducingsystem, the color is converted into proper data, such as R, G, and B, orY, C, M, and K, in accordance with the characteristics of thereproducing device on the reproduction point side. Therefore, the colorsof the image can be accurately reproduced regardless of the types ofreproducing devices.

In addition, the above-described color image recording and reproducingsystem can be used as a color image recording and reproducing systemcapable of optimum two-way communication in accordance with a situationin which data on a point side where the object image is photographed,and data on a point side where the object image is reproduced aremutually transmitted.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a schematic view of a system showing the whole arrangement andprocessing flow of a color image recording and reproducing systemaccording to the present invention;

FIG. 2 is a block diagram of the system showing a processing flowbetween the "photographing side" and the "reproduction side" in thecolor image recording and reproducing system of the present invention;

FIG. 3 is a block diagram of the system showing a system arrangement asthe first embodiment according to the present invention;

FIG. 4 is a view of the arrangement of a multispectral camera 10employing a rotary filter;

FIG. 5 is a block diagram showing the arrangement of an illuminationspectrum detecting section 20;

FIG. 6A is a block diagram showing the detailed arrangement of aprocessing device 30 on the photographing side;

FIG. 6B is a block diagram showing the detailed arrangement of aprocessing device 60 on the reproduction side;

FIG. 7A is a graph showing the "spectral characteristics" a of filer;

FIG. 7B is a graph showing the "spectrum distribution" obtained via thefilter;

FIG. 8 is a graph showing the "color matching function" of an XYZcolorimetric system as a human visual function;

FIG. 9 is a block diagram of the system showing a "two-way" systemarrangement as the second embodiment according to the present invention;

FIG. 10 is a block diagram showing the arrangement of a processingdevice 30 in the two-way color system of the second embodiment of thepresent invention;

FIG. 11 is a block diagram of a system showing the arrangement of acolor image recording and reproducing system as the third embodimentaccording to the present invention;

FIG. 12 is a block diagram showing the detailed arrangement of areproduction-side processing device 60 shown in FIG. 6A;

FIG. 13 is a block diagram showing an example of the arrangement of anarithmetic unit 35 of a photographing-side processing device 30 shown inFIG. 6A;

FIG. 14 is a view showing a modification of the arrangement of themultispectral camera 10 in FIG. 4; and

FIG. 15 is a view showing a modification of the arrangement of themultispectral camera 10 in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the presently preferredembodiments of the invention as illustrated in the accompanyingdrawings, in which like reference characters designate like orcorresponding parts throughout the several drawings.

First of all, a color image recording and reproducing system accordingto the present invention will be generally described with reference toFIG. 1.

FIG. 1 schematically shows the whole arrangement and processing flow ofthe color image recording and reproducing system according to thepresent invention.

More specifically, the color image recording and reproducing systemaccording to the present invention is a system for transferring colorimage information between at least two remote points apart from eachother.

For example, the color image recording and reproducing system formutually recording and reproducing color images between first and seconddifferent points apart from each other is constituted by respectiveconstituent sections for executing processing steps represented byblocks shown in FIG. 1.

More specifically, the color image recording and reproducing systemcomprises a spectral image pickup section 10 for executing a spectralimage pickup step (step S10) of photographing the image of an object tobe photographed as spectrum data in units of pixels, and a photographinglight spectrum detecting section 20 for executing a photographing lightspectrum detecting step (step S20) of detecting the spectrumdistribution (photographing light spectrum data) of illumination lightat the point where the image of the object is photographed.

This system further comprises a processing section 30 for receiving twopieces of information from the spectral image photographing section 10and the photographing light spectrum detecting section 20.

A reproduction environment light spectrum detecting section 70 forexecuting a reproduction environment light spectrum detecting step (stepS70) of detecting the spectrum distribution of illumination light at thesecond point (to be described later) where the image of the object isreproduced is externally connected to the processing section 30.

The processing section 30 is constituted by respective constituentelements for executing the following processing steps.

More specifically, the processing section 30 is constituted by aspectral reflectance distribution calculating section 30a for executinga spectral reflectance distribution calculating step (step S30a) ofeliminating influence of the spectrum distribution (photographing lightspectrum data) of the illumination light from the spectrum data, andcalculating the spectral reflectance distribution of the object, atransmitting means (not shown) for executing a reproduction environmentlight spectrum data transmitting step (not shown) of transmitting thereproduction environment light spectrum data of the second pointdetected in the reproduction environment light spectrum detecting step(step S70) to the first point, a spectrum converting section 30b forexecuting a spectrum converting step (step S30b) of calculating, on thebasis of the reproduction environment light spectrum data detected inthe reproduction environment light spectrum detecting step (step S70)and the data of the spectral reflectance distribution, a spectrumdistribution obtained when the image of the object is photographed underillumination light equivalent to that at the reproduction point side, avector imaging section 30c for executing a vector imaging step (stepS30c) of converting the spectrum distribution of each pixel calculatedin the spectrum converting step (step S30b) into three-dimensional colorspecification vector data, a transmitting means (not shown) forexecuting a color specification vector data transmitting step (notshown) of transmitting the color specification vector data to the secondpoint, and a color image reproducing section 30d for executing a colorimage reproducing step (step S30d) of reproducing and outputting a colorimage by means of display, printing, or the like on the basis of thecolor specification vector data.

In the color image recording and reproducing system of the presentinvention which executes the above-described color image recording andreproducing, information transmitted between the two exemplified pointsconsists of only the reproduction environment light spectrum data andthe color specification vector data whose data amounts are small.Therefore, the information amount is also small not to increase thetransmission capacity.

According to this system, it is possible to reproduce and output aphotographed image upon color reproduction in an accurate state at apoint such as a remote point different from the photographing point.

Detailed embodiments of the color image recording and reproducing systemaccording to the present invention will be sequentially described belowwith reference to the accompanying drawings.

(First Embodiment)

FIG. 2 shows the whole arrangement and processing flow of this system asthe first embodiment of the present invention.

The processing itself of this embodiment is the same as that in theabove general description with reference to FIG. 1. However, in thesystem arrangement of this embodiment, devices 10, 20, and 30A on the"photographing side" where a target object is observed and photographed,and devices 70 and 30B on the "reproduction side" where the photographedimage is reproduced are present apart from each other.

The devices on the photographing and reproduction sides are coupled viasome line and the like so as to allow data transmission.

Referring to FIG. 2, these "photographing side" devices 10, 20, and 30Aand these "reproduction side" devices 70 and 30B, which constitute thissystem, are assigned to respective processing steps and execute them asfollows.

First, a desired object illuminated by a predetermined light source isphotographed by a camera having a multispectral function (step S10).

That is, this photographing result is obtained by photographing theobject in a state wherein the spectrum of the light source illuminatingthe object and the actual object spectrum are multiplied with eachother.

The illumination spectrum in photographing is detected by thephotographing light spectrum detecting section 20 and the like on thephotographing side according to any method (step S20).

With the above-described processing, the image data obtained uponphotography contains a spectrum obtained upon multiplying both thespectrum of the illumination light source used in photographing and thereflection spectrum of the object.

The processing section 30A estimates that a component calculated bydividing the spectrum component of the obtained image data by theillumination spectrum component is the reflection spectrum of the object(step S30e).

At the same time, also on the reproduction side, the reproductionenvironment light spectrum detecting section 70 detects the illuminationspectrum of the reproduction-side environment for reproduction (stepS70).

The illumination spectrum information detected on the reproduction sideis sent to the photographing side via a transmission path.

At this point, correction of the illumination light source is completedon the photographing side, as described above. The reflection spectrumof the object itself free from the influence of the photographingillumination light source is generated.

The processing section 30A multiplies the reproduction-side illuminationspectrum sent from the reproduction side with the reflection spectrum ofthe object (step S30f).

With this processing, the spectrum information obtained on thephotographing side looks as if the object existed under thereproduction-side illumination.

The processing section 30A multiplies the spectrum data obtained in thismanner by the color matching function (e.g., a function exemplified inFIG. 8) of a properly selected colorimetric system and converts it intocolor specification vector data of three values (X, Y, and Z in FIG. 8;step S30g).

The color matching function of the colorimetric system frequently usedin general includes the XYZ colorimetric system and the L*a*bcolorimetric system.

The processing section 30A converts a multidimensional spectral imageinto a three-dimensional spectral image by multiplying the spectrum databy such a color matching function, and transmits the obtained image tothe reproduction-side device via the line.

The processing section 30B on the reproduction side converts thethree-dimensional color specification vector data transmitted from thephotographing side into color signals corresponding to the spectralcharacteristics (device values) of the reproducing device (step S60a),and displays an image (step S90).

In this case, as the device values of the reproducing device, alight-emitting display device such as a cathode-ray tube displaygenerally employs R, G, and B values, and a reflection device such as aprinter generally employs C, M, Y, and K values.

That is, the processing section 30B obtains in advance the relationshipbetween the output characteristics of the reproducing device and devicevalues input to this reproducing device. By using this relationship, theprocessing section 30B converts color specification vector data into thedevice values such that the color specification vector data accuratelyreproduce colors represented by the data, and performs display on amonitor or the like.

Note that functions of accurately reproducing the colors represented bythe color specification vector data have already been supported as a CMS(Color Management System) on the OS (Operation System) level of apersonal computer in consideration of the output characteristics of thereproducing device. These functions may be utilized.

The processing about the operation of the first embodiment of thissystem has been explained above.

FIG. 3 is a block diagram showing the system arrangement as the firstembodiment of the present invention.

With the system arrangement shown in FIG. 3, the above-mentionedprocessing flow is realized. For example, in this embodiment, the"photographing side" and the "reproduction side" are physically orspatially coupled to each other via a communication line.

More specifically, as shown in FIG. 3, the object is photographed by themultispectral camera 10 on the photographing side.

In this system, the illumination spectrum detector 20 is connected tothe processing device 30.

Similarly on the reproduction side, the illumination spectrum detector70 is connected to a processing device 60.

On the photographing side, the illumination spectrum detector 20 isseparately arranged, as shown in FIG. 3. However, if a white object as areference object, e.g., a white diffusion plate is photographed onceusing the multispectral camera 10 without arranging any illuminationspectrum detector 20, the photographing result can be used as anillumination spectrum.

The processing device 30 having such a means for detecting theillumination spectrum performs the following processing upon receptionof two pieces of information from the above-mentioned multispectralcamera 10 and illumination spectrum detector 20.

Image data processed by the processing device 30 is transmitted throughthe line via a communication interface device 40 and sent to theprocessing device 60 via a reproduction-side communication interfacedevice 45 at a remote point.

On the reproduction side, the illumination light spectrum on thereproduction side is detected in advance by the above-describedillumination spectrum detector 70. This illumination spectruminformation is reversely transmitted through the line and sent to thephotographing side.

On the basis of the entire image photographed in advance by themultispectral camera 10 and the illumination spectrum at that time, theprocessing device 30 on the photographing side performs correctionprocessing with this illumination light to leave only the reflectionspectrum component of the object.

Further, on the basis of illumination spectrum information sent from thereproduction side, the processing device 30 on the photographing sidemultiplies the reflection spectrum component by this value to convert itsuch that the illumination light becomes equivalent to the illuminationlight on the reproduction side. At the same time, the processing device30 sends information obtained by multiplying the reflection spectrumcomponent by three proper color matching functions as described above tothe processing device 60 on the reproduction side via the communicationinterface devices 40 and 45.

The processing device 60 on the reproduction side properly converts theinformation sent from the processing device 30 on the photographing sideso as to output and display accurate colors on a display device by theCMS function thereof like the one described above. Then, the processingdevice 60 displays an image on a display 90.

With this processing, colors faithful to the original colors of theobject are reproduced on the reproduction side. The observer is allowedto observe the object at a remote point as if the object is present infront of the observer's eyes.

FIG. 4 shows an example of the multispectral camera 10 using a rotaryfilter 2.

The rotary filter 2 like the one shown in FIG. 4 is a filter portionwith a plurality of filters each having spectral characteristics asrepresented by a curve in the graph of FIG. 7A.

When the object is photographed by the multispectral camera 10 via anoptical system 1 while rotating the rotary filter 2 by a motor 8, aspectrum distribution as represented by a curve in the graph of FIG. 7Bcan be obtained via a charge-coupled device (CCD) 3, ananalog-to-digital (A/D) converter 4, a frame memory 5, and an interface9.

A controller 7 controls the frame memory 5, a CCD driver 6, the motor 8,and the like.

FIG. 5 is a block diagram showing the arrangement of the illuminationspectrum detector 20 or 70 shown in FIG. 3.

Such an illumination spectrum detector is basically an element which canbe omitted on the photographing side by using the multispectral camera.However, the reproduction side requires any detector which detects theillumination light spectrum on only the reproduction side.

On the reproduction side, therefore, an illumination spectrum detectorhaving a function only for the purpose of more easily detecting theillumination light spectrum may be used in place of a complicated devicesuch as a multispectral camera.

As shown in FIG. 5, a transmission type white diffusion plate 21 as thereference object described above covers the front surfaces of aplurality of spectral filters 22 to give a uniform white light amount tothe plurality of spectral filters 22.

A plurality of photodiodes 23 are aligned behind the plurality ofspectral filters 22.

These photodiodes 23 are only normal photodiodes because an image neednot be picked up. However, the plurality of spectral filters 22 havingspectral characteristics different from each other need be arrangedbefore these photodiodes 23.

The respective photodiodes 23 are connected to a signal switch 28.

Signals corresponding to the characteristics of the respective spectralfilters 22 are output by sequentially switching the spectral filters 22by the signal switch 28.

The signals obtained by the respective spectral filters 22 are finallydigitized by an analog-to-digital (A/D) converter 29 connected to thesignal switch 28 and sent to the processing device (30; not shown).

FIG. 6A is a block diagram showing the detailed arrangement of theprocessing device 30 on the photographing side.

More specifically, the multispectral camera 10 and the illuminationspectrum detector 20 are externally connected to the processing device30, as shown in FIG. 6A.

The communication interface device 40 is arranged outside the processingsection 30 and connected to the reproduction-side device (not shown).

An image photographed by the multispectral camera 10 is the reflectedlight of the object obtained upon passing through the above-describedrotary filter 2 once, and generated as an image signal by the CCD 3shown in FIG. 4. Then, the image signal is transferred to the processingdevice 30 via the interface 9.

In the processing device 30, all the image data photographed using therespective filters of the rotary filter 2 are input to and temporarilystored in a spectral image frame memory 31, and then transferred to asubsequent interpolating unit 32.

The reason why the interpolating unit 32 is required will be explainedwith reference to FIG. 7B.

More specifically, normally, it is preferable in terms of the processingspeed in the processing device 30 that the number of filters of therotary filter 2 be as small as possible.

When the number of filters is decreased in consideration of theprocessing speed, processing of interpolating, e.g., middle point valuesbetween sampling points in a spectrum distribution like the one shown inFIG. 7B, i.e., interpolation processing for increasing the "number ofdimensions" is required to obtain a predetermined spectralcharacteristic. For this reason, the interpolating unit 32 is required.

After the image data having undergone the interpolation processing bythe interpolating unit 32 is input to and the temporarily stored in thespectrum memory 33, it is supplied to an arithmetic unit 35.

Note that the interpolating unit 32 can be eliminated by using a rotaryfilter having a sufficient number of filters.

Spectrum information about the spectrum of the light source used inphotographing is transferred by the illumination spectrum sensor 20 to aphotographing spectrum memory 34, and temporarily stored therein. Then,the spectrum information is supplied to the arithmetic unit 35.

As described above, the processing device 30 receives a spectrum likethe one indicated by a solid line in FIG. 7B from the multispectralcamera 10, and an illumination spectrum indicated by a broken line inFIG. 7B from the illumination spectrum sensor 20.

The illumination spectrum is input in the form of a curve like the oneindicated by the broken line in FIG. 7B.

The reflection spectrum is therefore obtained by dividing the value, ateach filter position, of the spectrum photographed as the entire imageby the multispectral camera 10, or an interpolated value by thisillumination spectrum value.

The method will be explained in detail using the following equation.

First, the element of a color specification vector P₁, P₂, P₃ ! of eachtransmitted pixel is expressed by ##EQU1## where L(λ): illuminationspectrum distribution on photographing side

E(λ): illumination spectrum distribution on reproduction side

S(λ): spectral reflectance of object to be photographed

P(λ): color matching function

S(λ)L(λ): spectrum distribution obtained by photographing

S(λ)E(λ): spectrum distribution obtained by photographing withreproduction-side illumination

Conversion of the color specification vector into a device color valueis expressed by the following equation: ##EQU2## for a to i aredetermined by the characteristics of a display device.

The device color value input at this time is corrected on thereproducing device side in accordance with the γ characteristic of thereproducing device.

When correction with γ is not performed in the reproducing device, thedevice color value to be input is determined by preparing in advance atable of input device color values and output device color values.

Note that the respective components in the above equation are simplyreferred to as follows for the sake of simplicity.

That is, L(λ) is simply referred to as L, which represents the componentof the illumination spectrum distribution on the photographing side.

E(λ) is simply referred to as E, which represents the component of theillumination spectrum distribution on the reproduction side.

S(λ) is simply referred to as S, which represents the spectralreflectance of the object.

P(λ) is simply referred to as P, which represents the color matchingfunction.

Normally, the spectrum distribution obtained by the multispectral camerais expressed by following relation: photographing illumination spectrumdistribution (L)×spectral reflectance (S) of object.

In this manner, since the obtained spectrum distribution is expressed byL·S, the spectral reflectance S of the object can be obtained bydividing L·S by L.

Upon calculation of the spectral reflectance S, information E of theillumination spectrum distribution on the reproduction side is sent tothe photographing side, and the spectral reflectance S is multiplied bythe value E. As a result, information S·E of the spectrum distributionof the object as if the object were photographed with theillumination-side spectrum can be obtained.

The series of processes are performed in the arithmetic unit 35 as acomponent of the processing device 30. The flow of the processing dataS, L, E, and P is shown in FIG. 13 (to be described later).

Thereafter, information to be transmitted to the reproduction side istransmitted in the form of three vectors. A function used to change theinformation into a vector is a "color matching function".

As an example of the "color matching function", there is a colormatching function for the XYZ colorimetric system (i.e., athree-dimensional space), like the one shown in FIG. 8.

More specifically, the color specification vector of each pixeltransmitted to the reproduction side can be calculated by equation (1)using such a color matching function.

FIG. 8 shows, as an example of color matching functions for theabove-described XYZ colorimetric system, three types of color matchingfunctions, i.e., x(λ) having two peaks around wavelengths of 440 nm and600 nm, y(λ) having a peak around a wavelength of 550 nm, and z(λ)having a peak around a wavelength of 450 nm.

If the spectrum distribution information S·E of the object is multipliedby these color matching functions, and the resultant values areintegrated within the range of visible light that man can see, lightcomponents present for the three vector values of the XYZ colorimetricsystems are obtained.

This method is a method for reflecting the human visual properties, andmore particularly, a method based on a principle of multiplying thefunctions of three values by each other, integrating them, andconverting spectrum information into three vectors on the basis of thefact that man has visual cells which perceive the three colors of theXYZ colorimetric system.

Upon this conversion, the photographing side reproduces and outputs theimage to be transmitted to the partner device on the reproduction side.

The processing operation of the photographing side (transmission side)has been described above.

Note that FIG. 13 shows a more detailed arrangement of thephotographing-side arithmetic unit 35 shown in FIG. 6A.

As shown in FIG. 13, the arithmetic unit 35 is constituted by a divider352 for receiving S·L and L respectively from the spectrum memory 33 andthe photographing spectrum memory 34, and dividing them, a colormatching function memory 351 holding a predetermined color matchingfunction, an adder 353 for receiving E from a reproduction spectrummemory 36 and adding it, and an integrator 354 for integrating theaddition result.

The reproduction spectrum memory 36 is a temporary storage means forholding reproduction-side illumination spectrum information E sent fromthe reproduction side.

A color image frame memory 37 is a temporary storage means fortemporarily holding image data represented by a color specificationvector upon the above-mentioned integration.

Note that the illumination spectrum represented by L or E in theabove-mentioned equation is not used for removal of illuminationnonuniformity or the like but is purely the spectrum of theillumination. For the processing, the illumination spectra are stored incorresponding memories.

As added in the block diagram of FIG. 6A showing the photographing side,for example, the photographing spectrum memory 34 stores theillumination spectrum L.

The spectrum memory 33 stores S·L.

The reproduction spectrum memory 36 stores E as the spectrumdistribution data on the reproduction side.

In the processing device 30 on the photographing side, the arithmeticunit 35 divides the value of the spectrum memory holding S·L by thevalue L stored in the photographing spectrum memory 34, multiplies thisquotient by the value E in the reproduction spectrum memory 36, furthermultiplies the obtained product by a color specification function P ofthe colorimetric system, and integrates the resultant value.

The element of the color specification vector of each pixel as theobtained result is stored in the color image frame memory 37 andtransmitted to the partner device via the communication interface device40.

The processing operation of the processing device 30 on thephotographing side has been described above.

Next, processing performed in the reproduction-side processing device 60shown in FIG. 6B will be explained.

More specifically, since this reproduction side mainly performs colorconversion, it uses only predetermined software of a system such as theCMS, as described above.

In this case, three-dimensional vectors are values represented by theXYZ colorimetric systems. These vectors are respectively multiplied byany matrix, e.g., predetermined coefficients, and added.

In this manner, the three-dimensional vectors are converted into valueswhich can be displayed on a device of an RGB system.

A matrix of a, b, c, d, e, f, g, h, and i in equation (2) is calculatedin advance on the basis of a correspondence relationship expressed bythe color specification value and device value of a single color using acolor table or the like.

By this processing, the color can be output to and displayed on thedisplay 90 by the values expressed by a certain display system, asdescribed above.

On the reproduction side shown in FIG. 6B, information sent from thephotographing side via the communication interface device 45 is input toan arithmetic unit 61 of a processing device 60.

A color conversion table 38 is a memory provided to hold in advance theabove-mentioned matrix of a, b, c, d, e, f, g, h, and i for colorconversion.

The reproduction-side illumination spectrum data obtained by theillumination spectrum sensor 70 is transmitted to the photographing sidevia the communication interface device 45.

Image information processed by the arithmetic unit 61 is output to anddisplayed on the external display 90 via a D/A converter 69 forconverting digital data into analog data.

When the image information is to be output for printing to a printer orthe like, there are four output values, i.e., Y, C, M, and K (Yellow,Cyan, Magenta, and blacK) values. In this case, a conversion matrix of4×3 is used in place of the matrix of 3×3.

(Modification)

In the first embodiment as described above, the multispectral camerashown in FIG. 4 uses a field sequential filter having a plurality ofdifferent spectrum distribution characteristics, such as the rotaryfilter 2. Instead of this, the multispectral camera may use, as amodification of FIG. 4, a transmission wavelength variable filter 2Aconstituted by a well-known liquid crystal, like the one shown in FIG.14, or an image pickup device using a mosaic filter having a pluralityof types of wavelength selection filters 2C having different spectralcharacteristics, like the one shown in FIG. 15.

(Function and Advantage 1)

According to the color image recording and reproducing system of thefirst embodiment, the following function and advantage can be obtained.

More specifically, according to this system, since the spectrum data ofa photographed image is converted and reproduced on the basis of thespectrum distribution of illumination light at the reproduction point(i.e., reproduction environment light spectrum data), the imagephotographed at a place different from the reproduction place can bedisplayed by accurate color reproduction or faithfully reproduced byprinting.

According to this system, since the image obtained as multidimensionalmultispectrum data is converted into three-dimensional colorspecification vectors and then transmitted, the image can be reproducedwith good color reproducibility at a place different from thephotographing place without increasing the data amount, compared to aconventional color image.

(Second Embodiment)

Next, a color image recording and reproducing system according to thesecond embodiment of the present invention will be described.

The above-described first embodiment is related to a one-way system suchas "medical diagnosis" in which the positions of the "photographingside" and the "reproducing side" are fixed for practical use. However,this embodiment is related to a "two-way" system in which the"photographing side" and the "reproduction side" are equal.

For this reason, the devices themselves are not discriminated as the"photographing side" and the "reproduction side", and are suitable forpractical use for two-way communication between different points such aspoints A and B, like the ones shown in FIG. 9.

Basically, the system of the second embodiment has the same functionalelements as those in the system of the above-described first embodiment.A detailed description will be omitted, and the characteristic featureof this embodiment will be explained below.

FIG. 9 is a block diagram showing the basic arrangement of the "two-way"color image recording and reproducing system as the second embodiment ofthe present invention.

In the system according to this embodiment which provides equalpractical use in the "two-way" manner without discriminating thephotographing side from the reproduction side, sets of photographingmultispectral cameras 10 and 80, displays 50 and 90 for display,illumination spectrum detectors 20 and 70 for detecting illuminationspectra, communication interfaces 40 and 45 for communication, andprocessing devices 30 and 60 for performing predetermined processing arerespectively arranged at, e.g., points A and B. The respective sets arearranged in at least two separate points, such as points A and B in thisembodiment, and constitute one system as a whole.

Further, as shown in FIG. 10, the arrangement of the processing device30 (60) in this embodiment is basically a combination of the constituentelements of the above-described photographing-side processing device 30shown in FIG. 6A, and the reproduction-side processing device 60.

Only the processing device 30 at point A will be described. Data of animage photographed by the multispectral camera 10 is stored once in aspectral image frame memory 31, and then stored in a spectrum memory 33upon an increase in number of dimensions via an interpolating unit 32.

The spectrum memory 33 stores information S·L, as described above.

On the other hand, the spectrum information of illumination lightobtained by the illumination spectrum sensor 20 is stored in aphotographing spectrum memory 34.

The spectrum memory 34 stores information L.

Illumination spectrum information on the partner side sent via thecommunication interface 40 is stored in a so-called reproductionspectrum memory 36.

Since the spectrum memory 33 stores the information S·L, an arithmeticunit 35 divides the information S·L by L in the above-described mannerto obtain the spectral reflectance S of the object, and multipliesinformation S by information E.

At this time, S is multiplied by E in the reproduction spectrum memory36.

Further, the value E·S is multiplied by a color matching function P forcolor reproduction, and integrated, thereby generating desired colorimage data.

Thereafter, the color image generated in this manner is transmitted tothe device on the partner side (point B) via the communication interface40.

On the other hand, the color recording and reproducing device at point Bhaving the same arrangement receives the transmitted data via thecommunication interface 45.

The received image information is expressed by, e.g., the XYZcolorimetric system with reference to a color conversion table 38, andso converted as to perform color reproduction suitable for the display90 of an RGB system.

The converted image information is multiplied by a predetermined matrixand converted into analog information via a D/A converter 39. Theresultant image information is output to and displayed on the display90.

(Function and Advantage 2)

According to the color image recording and reproducing system of thesecond embodiment, the following function and advantage can be obtained.

More specifically, according to this system, since data at a point sidewhere the image of an object is photographed, and data at a point sidewhere the object image is reproduced are mutually transmitted,information can be basically transmitted between the photographing andreproduction points in the two-way manner, and the color can always beaccurately reproduced on the reproduction side.

In addition, in the arrangement of this embodiment, the positions of thephotographing and reproduction sides can be alternately exchanged witheach other.

In the arrangement of this system, the photographing point side isequipped with at least the spectral image photographing means and thephotographing light spectrum detecting means, whereas the reproductionpoint side is equipped with at least the reproduction environment lightspectrum detecting means and the color image reproducing means.Remaining means have optimal arrangements in correspondence with thesituations of the respective positions, as needed.

(Third Embodiment)

Next, a color image recording and reproducing system as the thirdembodiment according to the present invention will be described.

FIG. 11 shows the arrangement of the color image recording andreproducing system as the third embodiment of the present invention.

As shown in FIG. 11, the system of the third embodiment is basically thesame as that in the first embodiment described above.

The system as the above-described first embodiment is an examplecharacterized by a function of basically adjusting only colors. However,when this system is actually used for medical treatment, the environmentof the reproduction side, i.e., the external environment of a display 90must be taken into consideration in terms of the human sense of vision.Information about the environment is very important to an improvement incolor reproducibility.

The environment includes various factors. In short, the colorreproducibility can be considered to be improved when an object isidentically observed on both the photographing and reproduction sides.

In this embodiment, only a true object is extracted from an imagephotographed on the photographing side, a background image on thereproduction side is synthesized on the image of only the object, andthe synthesized image is output. For example, in the medical field, theimage of only a patient is extracted as an object on the photographingside. On the reproduction side, a background image on the side of adoctor who observes the patient image is synthesized, and the resultantimage is output.

The reproduction side therefore requires at least one color camera 85for photographing the above-mentioned background as a constituentelement to be added to the arrangement of the system according to theabove-described first embodiment.

The arrangement of the third embodiment is different in this point fromthat of the above-described first embodiment.

A processing device 60 in the third embodiment requires a synthesizingmeans (not shown; synthesizing unit 65 to be described later), as amatter of course.

FIG. 12 shows the detailed arrangement of the reproduction-sideprocessing device 60 shown in FIG. 11.

The processing device 60 is basically similar to that in the firstembodiment. Image data sent via a communication interface 45 is input toan arithmetic unit 61.

In this embodiment, the image data is converted by the arithmetic unit61 into device color values for display. The image data converted intothe device values is stored in a frame memory 63.

Colors photographed by the color camera 85 are colors of the RGB system.These colors are not always equivalent to colors displayed on a displaydevice, i.e., a display 90. Therefore, predetermined correctionprocessing must be performed.

A background image, for the display 90, photographed by the color camera85 is converted by an arithmetic unit 62 into the device values of thedisplay 90 and stored in a frame memory 64.

A color conversion table 68 is a table storing both information aboutmatrix coefficients for converting the above-described colorspecification vectors into display device values and information aboutcoefficients for converting the R, G, and B values of a color imagephotographed by the color camera 85 into display device values.

After two pieces of image information output from the two frame memories63 and 64 are synthesized by the synthesizing unit 65, the synthesizedinformation undergoes conversion optimum for the display device (i.e.,the display 90) by a D/A converter 69. The converted information is sentto the display 90, and output and displayed.

There are various well-known methods of extracting an object to bephotographed.

For example, according to a certain method, the background image of aphotographing target is photographed in advance. A difference betweenthis image and an object is calculated. A changed portion is extractedas the object. Further, according to another method, in the case of amoving object such as man, a changed portion is extracted as the objecton the basis of a difference between two images photographed atdifferent times.

The object extracted using such a well-known method is stored in theframe memory 63.

The synthesizing unit 65 synthesizes the image data of the objectportion read out from the frame memory 63, and the image data of aportion, except for the object, read out from the frame memory 64, intoone image.

The synthesized image obtained in this manner is converted into analogdata by the D/A converter 69 and displayed on the display 90.

(Modification)

In the above-mentioned embodiment, the object image and the backgroundimage of the reproduction environment are converted into the devicevalues of the reproducing device, and synthesized. The synthesisprocessing of these images may use any coordinate system as far as theseimages are expressed by the same color specification coordinate system.

More specifically, the background image photographed by the color camera85 may be converted into the coordinate system (XYZ colorimetric systemin the first embodiment) of the color specification vector of theobject, and synthesized. The image as the synthesis result may beconverted into the device values of the display 90 and displayed.

In addition, the object image may be converted into the colorspecification coordinate system of the color camera 85, and synthesizedwith the background. The synthesized image may be converted into thedevice values of the display 90 and displayed.

As another modification, the background image of the reproductionenvironment may be photographed using a multispectral camera.

This case is particularly effective for the two-way system described inthe second embodiment because a special device need not be added.

(Function and Advantage 3)

According to the color image recording and reproducing system of thethird embodiment, the following function and advantage can be obtained.

More specifically, this system further comprises the display backgroundphotographing means for photographing the color image of the backgroundof the display device, and the image synthesizing means for convertingcolor specification vector data and the background color image into animage of a single colorimetric system, and synthesizing the convertedbackground color image and an object image. By reproducing thesynthesized image by the color image reproducing means, the backgroundcolor image of the reproducing device on the reproduction point side,and the object are converted into images under the same illuminationconditions. These images are synthesized, and the synthesized image isreproduced and output. Therefore, colors faithful to the colors of theobject are reproduced visually more accurately on the reproduction side.

For example, if this system is used for remote medical treatment or thelike, a patient as an object at a remote place is displayed as if thepatient were present in front of the doctor on the reproduction side. Amorbid portion of the patient can be observed with an original accuratecolor.

By using this system for remote medical treatment or the like,therefore, a remote medical system capable of performing a properdiagnosis, or the like can be realized.

(Other Modifications)

In addition to the plurality of embodiments and modifications, variousmodifications can be made within the range without departing from thegist of the present invention.

The present invention has been described on the basis of the first tothird embodiments. The present specification includes the followinginventions.

(1) A color image recording and reproducing system for reproducing, at adifferent remote place, an image recorded at an arbitrary place ischaracterized by comprising a spectral image photographing means forphotographing an object to be photographed as spectrum data in units ofpixels, a photographing light spectrum detecting means for detecting thespectrum distribution (to be referred to as photographing light spectrumdata hereinafter) of illumination light at a point where the object isphotographed, a reproduction environment light spectrum detecting meansfor detecting the spectrum distribution (to be referred to asreproduction environment light spectrum data hereinafter) ofillumination light of a point where the image of the object isreproduced, an image converting section for converting, on the basis ofthe photographing light spectrum data and the reproduction environmentlight spectrum data, the spectrum data into a color image obtained whenthe object is photographed under illumination light identical to that onthe reproduction point side, and a color image reproducing means forreproducing the color image data.

(1') A color image recording and reproducing system for reproducing, ata different place (e.g., remote place), an image recorded at anarbitrary place is characterized by comprising

a spectral image photographing means for photographing an object to bephotographed as spectrum data in units of pixels,

a photographing light spectrum detecting means for detecting thespectrum distribution (to be referred to as photographing light spectrumdata hereinafter) of illumination light at a point where the object isphotographed,

a spectral reflectance distribution calculating means for eliminatingthe influence of the photographing light spectrum data from the spectrumdata photographed by the spectral image photographing means, andcalculating the spectral reflectance distribution of the object,

a reproduction environment light spectrum detecting means for detectingthe spectrum distribution (to be referred to as reproduction environmentlight spectrum data hereinafter) of illumination light of a point wherethe image of the object is reproduced,

a spectrum converting means for calculating, on the basis of thespectral reflectance distribution and the reproduction environment lightspectrum data, a spectrum distribution obtained when the object isphotographed under illumination light identical to that on thereproduction point side,

a vector imaging means for converting a spectrum distributioncorresponding to each of the pixels calculated by the spectrumconverting means into three-dimensional color specification vector data,and

a color image reproducing means for reproducing a color image on thebasis of the color specification vector data.

(Function and Advantage 1)

According to the system defined in (1) and (1'), a photographed image isreproduced upon converting the spectrum data of the photographed imageon the basis of the spectrum distribution (i.e., reproductionenvironment light spectrum data) of illumination light at thereproduction point. Therefore, an image photographed at a place (e.g., aremote place) different from the reproduction place can be reproduced(displayed or printed) by accurate color reproduction.

(2) A color image recording and reproducing system defined in (1') ischaracterized in that the color image reproducing means comprises acolor converting means for converting the color specification vectordata into the device color value of a reproducing device on thereproduction point side.

(Function and Advantage 2)

According to the system defined in (2), the color is converted intoproper data, such as R, G, and B, or Y, C, M, and K, in accordance withthe characteristics of the reproducing device on the reproduction pointside. Therefore, an image photographed at a place (e.g., a remote place)different from the reproduction place can be reproduced (displayed orprinted) by accurate color reproduction regardless of the types ofreproducing devices.

(3) A color image recording and reproducing system defined in (1') ischaracterized by further comprising a transmitting means for mutuallytransmitting data on a point side where the image of the object isphotographed, and data on a point side where the image of the object isreproduced.

(Function and Advantage 3)

According to the system defined in (3), the data on the point side wherethe object image is photographed, and data on the point side where theobject image is reproduced are mutually transmitted. At least thespectral image photographing means and the photographing light spectrumdetecting means are arranged on the photographing point side. At leastthe reproduction environment light spectrum detecting means and thecolor image reproducing means are arranged on the reproduction pointside. Remaining means are arranged in accordance with various situationson the photographing and reproduction point sides. Therefore, an optimumsystem arrangement can be constructed.

(4) A color image recording and reproducing system defined in (1') to(3) is characterized in that the color image reproducing means comprisesa means for photographing the background image of a reproductionenvironment, and a color image synthesizing means for synthesizing thecolor specification vector data of the object and the reproductionenvironment.

(Function and Advantage 4)

According to the system defined in (4), a visually accurate colorexpression can be realized by synthesizing the background image of thedisplay device on the reproduction side with the object image convertedas if it were photographed under the illumination on the reproductionside, and displaying the synthesized image.

(5) A color image recording and reproducing system defined in (1') ischaracterized in that the spectral image photographing means is amultispectral camera using a field sequential filter having a pluralityof different spectrum distribution characteristics or a transmissionwavelength variable filter.

(Function and Advantage 5)

According to the system defined in (5), the spectrum data of the objectimage can be obtained with a high precision in units of pixels by usinga plurality of field sequential filters or a transmission wavelengthvariable filter consisting of, e.g., a liquid crystal.

(6) A color image recording and reproducing system defined in (1') ischaracterized in that the spectral image photographing means is amultispectral camera using an image pickup device using a mosaic filterhaving a plurality of types of filters with different spectralcharacteristics.

(Function and Advantage 6)

According to the system defined in (6), the spectrum data of the objectimage can be obtained by one photographing operation or photographingoperations whose number of times is smaller than the number of types ofspectral characteristics of a filter to be used. Therefore, a high-speedsystem can be constructed, and the image pickup device can be downsized.

(7) A color image recording and reproducing system defined in (1') ischaracterized in that the vector imaging means calculates, using thecolor matching function distribution of three stimulus values of apredetermined colorimetric system stored in a storage means in advance,the spectrum distribution obtained when the image obtained by thespectrum converting means is photographed in units of pixels underillumination light identical to that on the reproduction side.

(Function and Advantage 7)

According to the system defined in (7), an accurate color expression canbe performed independently of the characteristics of the spectral imagephotographing means by using the color matching function distribution(e.g., X, Y, and Z, or L*a*b*) of three stimulus values of apredetermined colorimetric system.

(8) A color image recording and reproducing system defined in (1') ischaracterized in that the photographing light spectrum detecting meansdetects the photographing light spectrum by photographing a referencetarget having a predetermined spectral reflectance distribution usingthe spectral image photographing means.

(Function and Advantage 8)

According to the system defined in (8), the arrangement of the apparatuscan be simplified by using the spectral image photographing means as aphotographing light spectrum detecting means.

(9) Color image recording and reproducing systems for mutually recordingand reproducing images between first and second different points arecharacterized in that

each color image recording and reproducing system is constituted by

a spectral image photographing means for photographing an object to bephotographed as spectrum data in units of pixels,

a photographing light spectrum detecting means for detecting thespectrum distribution (to be referred to as photographing light spectrumdata hereinafter) of illumination light at a point where the object isphotographed,

a spectral reflectance distribution calculating means for eliminatingthe influence of the photographing light spectrum data from the spectrumdata photographed by the spectral image photographing means, andcalculating the spectral reflectance distribution of the object,

a reproduction environment light spectrum detecting means for detectingthe spectrum distribution (to be referred to as reproduction environmentlight spectrum data hereinafter) of illumination light of a point wherethe object is reproduced,

a spectrum converting means for calculating, on the basis of thespectral reflectance distribution and the reproduction environment lightspectrum data, a spectrum distribution obtained when the object isphotographed under illumination light identical to that on thereproduction point side, and

a vector imaging means for converting a spectrum distributioncorresponding to each pixel calculated by the spectrum converting meansinto three-dimensional color specification vector data,

wherein the color image recording and reproducing systems arerespectively arranged at the first and second points, and

the color image recording and reproducing systems further comprisetransmitting means for mutually transmitting the reproductionenvironment light spectrum data and the color specification vector databetween the first point and the second point.

(Function and Advantage 9)

According to the system defined in (9), images photographed at twodifferent points can be transmitted in a two-way manner by accuratecolor reproduction.

(10) Color image recording and reproducing systems defined in (9) arecharacterized in that the color image reproducing means comprises acolor converting means for converting the color specification vectordata into the device color values of a reproducing device on thereproduction point side.

(Function and Advantage 10)

According to the system defined in (10), the colors are converted intoproper data, such as R, G, and B, or Y, C, M, and K, in accordance withthe characteristics of the reproducing device on the reproduction pointside. Therefore, an image photographed at a place (e.g., a remote place)different from the reproduction place can be reproduced (displayed orprinted) by accurate color reproduction regardless of the types ofreproducing devices. (11) Color image recording and reproducing systemsdefined in (1') or (9) are characterized by further comprising a displaybackground photographing means for photographing the color image of abackground of a display device, and an image synthesizing means forconverting the color specification vector data and background colorimage data into images of a single colorimetric system, and synthesizingthe converted background color image and the image of the object,

so that the color image reproducing means reproduces and displays thesynthesized image.

(Function and Advantage 11)

According to the system defined in (11), the color image of thebackground of the reproducing device on the reproduction point side, andthe object image are synthesized and reproduced upon conversion into thesame illumination condition. Therefore, the image can be reproduced(displayed or printed) by visually more accurate color reproduction.

(12) A color image recording and reproducing system defined in (11) ischaracterized in that, after converting the three-dimensional colorspecification vector data of the object and the background color imagedata into the device color values of the reproducing device, the imagesynthesizing means synthesizes the background color image and the objectimage.

(Function and Advantage 12)

According to the system defined in (12), after the object image isconverted into the device color values, it is synthesized in accordancewith the color image data of the background of the reproducing device onthe reproduction point side. Therefore, the image can be reproduced(displayed or printed) by more accurate color reproduction.

(13) A color image recording and reproducing system defined in (11) ischaracterized in that, after converting the background color image intothe expression of a colorimetric system on the object side, synthesizingthe converted image, and converting the synthesized image into thedevice color values of the reproducing device, the image synthesizingmeans reproduces and displays the converted image.

(Function and Advantage 13)

According to the system defined in (13), after the color image data ofthe background of the reproducing device on the reproduction point sideis converted into the data of the colorimetric system for the objectimage, and the converted image is synthesized, the synthesized image isconverted into the device color values and reproduced. Therefore, theimage can be reproduced (displayed or printed) by visually more accuratecolor reproduction.

(14) A color image recording and reproducing system defined in (11) ischaracterized in that, after converting the color specification vectordata into the device color values of the display backgroundphotographing means, synthesizing the converted image, and furtherconverting the synthesized image into the device color values of thereproducing device, the image synthesizing means reproduces and displaysthe image.

(Function and Advantage 14)

According to the system defined in (14), the color specification vectordata of the object are converted into the device color values of thedisplay background photographing means, and the converted data aresynthesized. Therefore, the image can be reproduced (displayed orprinted) by visually more accurate color reproduction.

(15) A color image recording and reproducing method of mutuallyrecording and reproducing images between first and second two differentpoints is characterized by comprising

the spectral image photographing step of photographing an object to bephotographed as spectrum data at the first point in units of pixels,

the photographing light spectrum detecting step of detecting thespectrum distribution (to be referred to as photographing light spectrumdata hereinafter) of illumination light at a point where the object isphotographed,

the spectral reflectance distribution calculating step of eliminatingthe influence of the photographing light spectrum data from the spectrumdata photographed in the spectral image photographing step, andcalculating the spectral reflectance distribution of the object,

the reproduction environment light spectrum detecting step of detectinga spectrum distribution (to be referred to as reproduction environmentlight spectrum data hereinafter) of illumination light at the secondpoint where an image of the object is reproduced,

the reproduction environment light spectrum data transmitting step oftransmitting the reproduction environment light spectrum data at thesecond point detected in the reproduction environment light spectrumdetecting step to the first point,

the spectrum converting step of calculating, on the basis of thereproduction environment light spectrum data transmitted in thereproduction environment light spectrum data transmitting step, and thedata of the spectral reflectance distribution, a spectrum distributionobtained when the object is photographed under illumination lightidentical to that on the reproduction point side,

the vector imaging step of converting a spectrum distribution of each ofthe pixels calculated by the spectrum converting means intothree-dimensional color specification vector data,

the color specification vector data transmitting step of transmittingthe color specification vector data to the second point, and

the color image reproducing step of reproducing (e.g., displaying orprinting) a color image on the basis of the color specification vectordata.

(Function and Advantage 15)

According to the system defined in (15), only the reproductionenvironment light spectrum data and the color specification vector datawhich are small in data amount are transmitted between the two points.Therefore, an image photographed at a place (e.g., a remote place)different from the reproduction place can be reproduced (displayed orprinted) by accurate color reproduction without increasing thetransmission capacity.

(16) A color image recording and reproducing method defined in (15) ischaracterized in that the color image reproducing step comprises thecolor converting step of converting the color specification vector datainto the device color values of a reproducing device on the reproductionpoint side.

(Function and Advantage 16)

According to the system defined in (16), the colors are converted intoproper data, such as R, G, and B, or Y, C, M, and K, in accordance withthe characteristics of the reproducing device on the reproduction pointside. Therefore, an image photographed at a place (e.g., a remote place)different from the reproduction place can be reproduced (displayed orprinted) by accurate color reproduction regardless of the types ofreproducing devices.

(17) Color image recording and reproducing systems defined in (11) arecharacterized in that the display background photographing means is amultispectral camera.

(Function and Advantage 17)

According to the system defined in (17), in the case of a two-waysystem, the image can be reproduced (displayed or printed) by visuallymore accurate color expression without adding a special device.

As has been described above, according to the present invention, inreproducing an image photographed at a remote place, the colors can beaccurately reproduced even with a small amount of the informationtransmitted between the photographing and reproduction places. Thetransmission capacity does not increase. At a place, e.g., a remoteplace, different from the reproduction place, the colors of thephotographed image can be accurately reproduced. The image can bereproduced and output by display, printing, or the like.

According to the present invention, the color is converted into properdata in accordance with the characteristics of the reproducing device.Therefore, there can be provided a color image recording and reproducingsystem constituted by an apparatus which realizes a color imagerecording and reproducing method capable of always faithfullyreproducing and outputting the image by display or printing regardlessof the types of reproducing devices.

Additional embodiments of the present invention will be apparent tothose skilled in the art from consideration of the specification andpractice of the presence invention disclosed herein. It is intended thatthe specification and examples be considered as exemplary only, with thetrue scope of the present invention being indicated by the followingclaims.

What is claimed is:
 1. A color image recording and reproducing systemfor reproducing, at a different remote place, an image recorded at anarbitrary place, comprising:spectral image photographing means forphotographing an object to be photographed as spectrum data in units ofpixels; photographing light spectrum detecting means for detecting aphotographing light spectrum data including data on a spectrumdistribution of illumination light at a point where said object isphotographed by said spectral image photographing means; reproductionenvironment light spectrum detecting means for detecting reproductionenvironment light spectrum data including data on a spectrumdistribution of illumination light at a reproduction point side whichincludes a point where an image of said object photographed by saidspectral image photographing means is reproduced; image converting meansfor converting, on the basis of the photographing light spectrum datadetected by said photographing light spectrum detecting means and thereproduction environment light spectrum data detected by saidreproduction environment light spectrum detecting means, the spectrumdata photographed by said spectral image photographing means into colorimage data equivalent to color image data obtained when said object isphotographed under illumination light substantially identical to that onthe reproduction point side; and color image reproducing means forreproducing the color image data converted by said image convertingmeans.
 2. A color image recording and reproducing system according toclaim 1, wherein said image converting means comprises:spectralreflectance distribution calculating means for eliminating an influenceof the photographing light spectrum data detected by said photographinglight spectrum detecting means from the spectrum data photographed bysaid spectral image photographing means, and calculating a spectralreflectance distribution of said object; spectrum converting means forcalculating, based on the spectral reflectance distribution calculatedby said spectral reflectance distribution calculating means and anoutput of said reproduction environment light spectrum detecting means,a spectrum distribution obtained when said object is photographed underillumination light substantially identical to that on the reproductionpoint side; and vector imaging means for converting a spectrumdistribution corresponding to each of said pixels calculated by saidspectrum converting means into three-dimensional color specificationvector data; and wherein said color image reproducing means reproduces acolor image of said object based on the color specification vector dataproduced by said vector imaging means.
 3. A color image recording andreproducing system according to claim 2, wherein said color imagereproducing means comprises color converting means for converting thecolor specification vector data into a device color value of areproducing device on the reproduction point side.
 4. A color imagerecording and reproducing system according to claim 2, furthercomprising transmitting means for mutually transmitting data on a pointside where the image of said object is photographed, and data on a pointside where the image of said object is reproduced.
 5. A color imagerecording and reproducing system according to claim 2, wherein saidcolor image reproducing means comprises:means for photographing abackground image of a reproduction environment; and color imagesynthesizing means for synthesizing the color specification vector dataof said object and the reproduction environment light spectrum data. 6.A color image recording and reproducing system according to claim 2,wherein said spectral image photographing means includes a multispectralcamera comprising one of (i) a field sequential filter having aplurality of different spectrum distribution characteristics and (ii) atransmission wavelength variable filter.
 7. A color image recording andreproducing system according to claim 2, wherein said spectral imagephotographing means includes a multispectral camera comprising an imagepickup device using a mosaic filter having a plurality of types offilters with different spectral characteristics.
 8. A color imagerecording and reproducing system according to claim 2, wherein saidvector imaging means calculates, on the basis of a color matchingfunction distribution of three stimulus values of a predeterminedcolorimetric system stored in a storage means in advance, the spectrumdistribution of each of said pixels obtained when the image of saidobject obtained by said spectrum converting means is photographed underillumination light identical to that on the reproduction point side. 9.A color image recording and reproducing system according to claim 2,wherein said photographing light spectrum detecting means detects thephotographing light spectrum by photographing a reference target havinga predetermined spectral reflectance distribution using said spectralimage photographing means.
 10. Color image recording and reproducingsystems according to claim 1, wherein said image converting meansfurther comprises:spectral reflectance distribution calculating meansfor eliminating an influence of the photographing light spectrum datadetected by said photographing light spectrum detecting means from thespectrum data photographed by said spectral image photographing means,and calculating a spectral reflectance distribution of said object;spectrum converting means for calculating, on the basis of the spectralreflectance distribution calculated by said spectral reflectancedistribution calculating means and an output of said reproductionenvironment light spectrum detecting means, a spectrum distributionobtained when said object is photographed under illumination lightsubstantially identical to that on the reproduction point side; andvector imaging means for converting a spectrum distributioncorresponding to each of said pixels calculated by said spectrumconverting means into three-dimensional color specification vector data;and wherein said color image reproducing means reproduces a color imageof said object on the basis of the color specification vector dataproduced by said vector imaging means.
 11. Color image recording andreproducing systems according to claim 10, wherein said color imagereproducing means comprises color converting means for converting thecolor specification vector data into device color values of areproducing device on the reproduction point side.
 12. Color imagerecording and reproducing systems according to claim 2 or 10, furthercomprising:display background photographing means for photographing acolor image of a background of a display device; and image synthesizingmeans for converting the color specification vector data produced bysaid vector imaging means and background color image data photographedby said display background photographing means into images of a singlecolorimetric system, and synthesizing the converted background colorimage data and image data of said object, so that said color imagereproducing means reproduces and displays an image synthesized by saidimage synthesizing means.
 13. Color image recording and reproducingsystems according to claim 12, wherein, after converting thethree-dimensional color specification vector data of said object and thebackground color image data into device color values of said reproducingdevice, said image synthesizing means synthesizes the background colorimage data and the three-dimensional color specification vector data.14. Color image recording and reproducing systems according to claim 12,wherein, after converting the background color image data into anexpression of a colorimetric system on the object side, synthesizing theconverted data with the three-dimensional color specification vectordata of said object, and converting the synthesized image data intodevice color values of said reproducing device, said image synthesizingmeans reproduces and displays the converted image data.
 15. Color imagerecording and reproducing systems according to claim 12, wherein, afterconverting the color specification vector data into device color valuesof said display background photographing means, synthesizing theconverted data with the background color image data, and furtherconverting the synthesized image data into device color values of saidreproducing device, said image synthesizing means reproduces anddisplays the image data.
 16. A color image recording and reproducingmethod of mutually recording and reproducing images between first andsecond different points, according to claim 1, wherein said imageconverting step comprises:a spectral reflectance distributioncalculating step of eliminating an influence of the photographing lightspectrum data detected in the photographing light spectrum detectingstep from the spectrum data photographed in the spectral imagephotographing step, and calculating a spectral reflectance distributionof said object; a spectrum converting step of calculating, on the basisof the spectral reflectance distribution calculated in the spectralreflectance distribution calculating step and a result of thereproduction environment light spectrum detecting step, a spectrumdistribution obtained when said object is photographed underillumination light substantially identical to that on the second pointside; a vector imaging step of converting a spectrum distributioncorresponding to each of said pixels calculated in the spectrumconverting step into three-dimensional color specification vector data;and wherein the color image reproducing step reproduces a color image ofsaid object on the basis of the color specification vector data producedin the vector imaging step.
 17. A color image recording and reproducingmethod according to claim 16, wherein the color image reproducing stepcomprises a color image converting step of converting the colorspecification vector data into device color values of a reproducingdevice on the second point side.
 18. Color image recording andreproducing systems according to claim 12, wherein said displaybackground photographing means comprises a multispectral camera. 19.Color image recording and reproducing systems for mutually recording andreproducing images between first and second different points,wherein:each color image recording and reproducing systemcomprises:spectral image photographing means for photographing an objectto be photographed as spectrum data in units of pixels; photographinglight spectrum detecting means for detecting photographing lightspectrum data including data on a spectrum distribution of illuminationlight at a point where said object is photographed by said spectralimage photographing means; reproduction environment light spectrumdetecting means for detecting reproduction environment light spectrumdata including data on a spectrum distribution of illumination light ata reproduction point side which includes a point where an image of saidobject photographed by said spectral image photographing means isreproduced; image converting means for converting, on the basis of thephotographing light spectrum data detected by said photographing lightspectrum detecting means and the reproduction environment light spectrumdata detected by said reproduction environment light spectrum detectingmeans, the spectrum data photographed by said spectral imagephotographing means into color image data equivalent to color image dataobtained when said object is photographed under illumination lightsubstantially identical to that on the reproduction point side; colorimage reproducing means for reproducing the color image data convertedby said image converting means, wherein said color image recording andreproducing systems are respectively arranged at said first and seconddifferent points; and said color image recording and reproducing systemsfurther comprise transmitting means for mutually transmitting thereproduction environment light spectrum data and the color specificationvector data between the first point and the second point.
 20. A colorimage recording and reproducing method of mutually recording andreproducing images between first and second different points,comprising:a spectral image photographing step of photographing anobject to be photographed as spectrum data at the first point in unitsof pixels; a photographing light spectrum detecting step of detectingphotographing light spectrum data which includes a spectrum distributionof illumination light at a point where said object is photographed; areproduction environment light spectrum detecting step of detectingreproduction environment light spectrum data including data on aspectrum distribution of illumination light at the second point where animage of said object is reproduced; a reproduction environment lightspectrum data transmitting step of transmitting the reproductionenvironment light spectrum data at the second point detected in thereproduction environment light spectrum detecting step to the firstpoint; an image converting step of converting, on the basis of thephotographing light spectrum data detected in the photographing lightspectrum detecting step and the reproduction environment light spectrumdata detected in the reproduction environment light spectrum detectingstep, the spectrum data photographed in said spectral imagephotographing step into color image data equivalent to color image dataobtained when said object is photographed under illumination lightsubstantially identical to that on the reproduction point side; and acolor image reproducing step of reproducing the color image dataconverted in said image converting step.